Battery device, electronic apparatus, and battery system

ABSTRACT

Disclosed is a battery device including a battery enclosure incorporating a battery cell. The battery device further includes an output terminal that outputs power of the battery cell. The battery enclosure includes a first surface, a second surface, a first step surface, a second step surface, a first engaging portion, a second engaging portion, a first groove, and a second groove formed in the second step surface and the second engaging portion, and a recess is provided in at least one of the first step surface and the second step surface.

CROSS REFERENCES TO RELATED APPLICATIONS

The present application is a continuation application of and claims the benefit of priority under 35 U.S.C. §120 from U.S. application Ser. No. 13/458,601, filed Apr. 27, 2012, which is a continuation application of U.S. application Ser. No. 13/116,781, now U.S. Pat. No. 8,241,774, filed May 26, 2011, which is a continuation application of U.S. application Ser. No. 11/836,310, now U.S. Pat. No. 7,989,101, filed Aug. 9, 2007, which is based upon and claims the benefit of priority under 35 U.S.C. §119 from prior Japanese Patent Application JP 2006-230797, filed in the Japanese Patent Office on Aug. 28, 2006. The entire contents of each of the above is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a battery device used as a portable power source, an electronic apparatus in which the battery device is detachably mounted and used, and a battery system including a combination of the electronic apparatus with the battery device.

2. Description of the Related Art

Japanese Unexamined Patent Application Publication No. 2000-243365 discloses an example of a battery device of the related art as a portable power source. Japanese Unexamined Patent Application Publication No. 2000-243365 discloses a battery pack in which a rechargeable battery cell used as a power source for an electronic apparatus is stored; a battery mounting device on which the battery pack is mounted; and an electronic apparatus including a battery mounting mechanism on which the battery pack is mounted. The battery pack disclosed in Japanese Unexamined Patent Application Publication No. 2000-243365 includes “a battery cell; a case in which the battery cell is stored; an output terminal which is provided in the case and outputs power of the battery cell; and a second surface of the case which is provided continuously with a first surface of the case having the output terminal and provided approximately perpendicular to the first surface, where a recess is formed with a plurality of steps in an approximate center of the second surface”.

It may be expected that the battery pack having such a configuration may be prevented from being inappropriately mounted on a battery mounting device which is supposed to be incompatible (paragraph [0161] of the specification), for example.

Japanese Unexamined Utility Model Application Publication No. 2005-190929 discloses another example of a battery device of the related art. Japanese Unexamined Utility Model Application Publication No. 2005-190929 discloses a battery device and an electronic apparatus operated using the battery device. The battery device disclosed in Japanese Unexamined Utility Model Application Publication No. 2005-190929 includes “a case having a width, a thickness, and a length; a rechargeable battery provided in the case; and a battery side terminal provided on a surface of the case and connected to the rechargeable battery, where the battery device is inserted in the length direction into a battery housing chamber of an electronic apparatus and the battery side terminal is connected to a housing chamber side terminal of the battery housing chamber. A guide groove is formed in each side of the case in the crosswise direction, where the guide groove extends in the length direction and is engaged with a protrusion provided in the battery housing chamber to position the case in the thickness direction in the battery housing chamber”.

According to the battery device having such a configuration, it may be expected that “since a guide groove is formed in each side of the case in the crosswise direction of the battery device, where the guide groove extends in the length direction and is engaged with a protrusion provided in the battery housing chamber to position the case in the thickness direction in the battery housing chamber, it is possible to store, in the battery housing chamber, multiple types of battery devices different in thickness of the case, that is, different in volume” (paragraph [0005] of the specification).

However, in the battery device disclosed in Japanese Unexamined Patent Application Publication No. 2000-243365, a recess formed with a plurality of steps is provided in an approximate center of a rear surface of the case in which the battery cell is stored, and a protrusion corresponding to a shape of the recess is provided in a mounting portion of the electronic apparatus in which the battery device is mounted, in order to discriminate a type of the battery device. As a result, when a new battery device is developed, it may be necessary to increase the number of the steps in the recess of the battery device and provide a protrusion corresponding to the recess in the mounting portion of the electronic apparatus, and thus the recess of the battery device and the protrusion of the mounting portion have complicated shapes.

Further, each of the battery devices disclosed in Japanese Unexamined Patent Application Publication No. 2000-243365 and Japanese Unexamined Patent Application Publication No. 2005-190929 is formed as an exclusive component that may be mounted only on a mounting portion having a specific configuration of an electronic apparatus. Accordingly, one battery device may be mounted on an electronic apparatus having a mounting portion corresponding to the battery device, and a battery device corresponding to the electronic apparatus may separately be prepared for another type of an electronic apparatus including a mounting portion having a different mounting structure.

SUMMARY OF THE INVENTION

The number of steps in a recess of the battery device may have to be increased and provided a protrusion corresponding to the recess in amounting portion of an electronic apparatus when a new battery device of the related art is developed, and thus the recess of the battery device and the protrusion of the mounting portion have complicated shapes.

A battery device according to an embodiment of the present invention includes an approximately rectangular parallelepiped battery enclosure incorporating a battery cell; and an output terminal which is placed to expose an output portion in an approximate center of at least a first surface of the battery enclosure in a crosswise direction and outputs power of the battery cell. The battery enclosure has a second surface, a first step surface, a second step surface, a first engaging portion, a second engaging portion, a first groove, and a second groove. The second surface is approximately perpendicular to the first surface. The first step surface is provided continuously with and approximately parallel to the second surface with a predetermined step on one side of the second surface in the crosswise direction. The second step surface is provided continuously with and approximately parallel to the second surface with a predetermined step on the other side of the second surface in the crosswise direction. The first engaging portion protrudes with predetermined width and thickness from the second surface to one side in the crosswise direction. The second engaging portion protrudes with predetermined width and thickness from the second surface in the crosswise direction to the other side. The first groove is formed with the first step surface and the first engaging portion. The second groove is formed with the second step surface and the second engaging portion. The most important feature is that a recess is provided in at least one of the first step surface and the second step surface.

An electronic apparatus according to an embodiment of the present invention includes a mounting portion in which a battery device is detachably mounted having an approximately rectangular parallelepiped battery enclosure incorporating a battery cell; and a connection terminal which is placed to expose a connection portion in an approximate center of at least a first surface of the mounting portion in a crosswise direction and is detachably connected to an output terminal that outputs power of the battery cell of the battery device. The mounting portion of the electronic apparatus has a second surface approximately perpendicular to the first surface; a first hook provided at a predetermined interval from the second surface and detachably engaged with a first engaging portion provided in the battery enclosure; and a second hook provided at a predetermined interval from the second surface and detachably engaged with a second engaging portion provided in the battery enclosure. A projection protruding away from the second surface is provided on at least one of the first hook and the second hook.

According to an embodiment of the present invention, there is provided a battery system including a combination of a battery device having a battery cell with an electronic apparatus having a mounting portion in which the battery device is detachably mounted.

The battery device has an approximately rectangular parallelepiped battery enclosure incorporating a battery cell; and an output terminal which is placed to expose an output portion in an approximate center in a crosswise direction of at least a battery side first surface of the battery enclosure and outputs power of the battery cell. The battery enclosure of the battery device has a battery side second surface, a first step surface, a second step surface, a first engaging portion, a second engaging portion, a first groove, and a second groove. The battery side second surface is approximately perpendicular to the battery side first surface. The first step surface is provided continuously with and approximately parallel to the battery side second surface with a predetermined step on one side of the battery side second surface in the crosswise direction. The second step surface is provided continuously with and approximately parallel to the battery side second surface with a predetermined step on the other side of the battery side second surface in the crosswise direction. The first engaging portion protrudes with predetermined width and thickness to one side from the battery side second surface in the crosswise direction. The second engaging portion protrudes with predetermined width and thickness to the other side from the battery side second surface in the crosswise direction. The first groove is formed with the first step surface and the first engaging portion. The second groove is formed with the second step surface and the second engaging portion. A recess is provided in at least one of the first step surface and the second step surface.

The electronic apparatus has a connection terminal which is placed to expose a connection portion in an approximate center of at least an electronic apparatus side first surface of the mounting portion in a crosswise direction and is detachably connected to the output terminal that outputs power of the battery cell of the battery device. The mounting portion of the electronic apparatus has: an electronic apparatus side second surface approximately perpendicular to the electronic apparatus side first surface; a first hook provided at a predetermined interval from the electronic apparatus side second surface and detachably engaged with a first engaging portion provided in the battery enclosure; and a second hook provided at a predetermined interval from the electronic apparatus side second surface and detachably engaged with a second engaging portion provided in the battery enclosure. A projection detachably engaged with the recess is provided in at least one of the first hook and the second hook.

A battery device according to an embodiment of the present invention having such a configuration may provide a type discrimination portion for a new battery device with a simple structure and may be commonly used for multiple types of an electronic apparatus having different mounting systems. An electronic apparatus according to an embodiment of the present invention may provide a type discrimination portion for a new battery device with a simple structure, and a battery device mounted on a mounting portion of the electronic apparatus to supply power may be commonly used for multiple types of the electronic apparatus having different mounting systems. Further, a battery system according to an embodiment of the present invention including a combination of the battery device and the electronic apparatus described above may provide a battery system having advantages of the battery device and the electronic apparatus.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a bottom oblique view showing a first example of a battery device according to an embodiment of the present invention.

FIGS. 2A-2B show a first example of a battery device according to an embodiment of the present invention, where FIG. 2A is a bottom view and FIG. 2B is a left side view.

FIGS. 3A-3C show a first example of a battery device according to an embodiment of the present invention, where FIG. 3A is a front view, FIG. 3B is a rear view, and FIG. 3C is a D-D line cross-sectional view of FIG. 2B.

FIG. 4 is a front oblique view of a digital video camera as a specific example of an imaging device shown as an example of an electronic apparatus according to an embodiment of the present invention.

FIG. 5 is a rear oblique view of a digital video camera as a specific example of an imaging device shown as an example of an electronic apparatus according to an embodiment of the present invention.

FIG. 6 is a rear view of a digital video camera as a specific example of an imaging device shown as an example of an electronic apparatus according to an embodiment of the present invention.

FIG. 7 is an oblique view of a rear panel having a mounting portion of the digital video camera shown in FIG. 4.

FIG. 8 is an exploded oblique view of a rear panel having a mounting portion, a slide member, and a support plate member of the digital video camera shown in FIG. 4.

FIGS. 9A-9C show the rear panel shown in FIG. 7 and others, where FIG. 9A is a front view of the rear panel, FIG. 9B is a view describing an initial state during mounting a battery device, and FIG. 9C is view describing a state after mounting the battery device.

FIG. 10 is an oblique view showing a second example of a rear panel having a mounting portion of an imaging device shown as an example of an electronic apparatus according to an embodiment of the present invention.

FIGS. 11A-11C show the rear panel shown in FIG. 10 and others, where FIG. 11A is a front view of the rear panel, FIG. 11B is a view describing an initial state during mounting a battery device, and FIG. 11C is view describing a state after mounting the battery device.

FIG. 12 is a bottom oblique view showing a second example of a battery device according to an embodiment of the present invention.

FIG. 13 is a front view showing a second example of a battery device according to an embodiment of the present invention.

FIG. 14 is an oblique view showing a third example of a rear panel having a mounting portion of an imaging device shown as an example of an electronic apparatus according to an embodiment of the present invention.

FIG. 15 is an U-U line cross-sectional view showing the rear panel shown in FIG. 14 and others in a state where a battery device is mounted.

FIG. 16 is a front oblique view showing a fourth example of a mounting portion of an electronic apparatus according to an embodiment of the present invention.

FIG. 17 is a cross-sectional view of a mounting portion of a fourth example in which a battery device is mounted, the mounting portion having a dimension in a height direction Z2 sufficiently larger than that of the battery device.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

A battery device, suitable electronic apparatus using the battery device, and a battery system including a combination of the battery device with the electronic apparatus are realized based on a simple structure, where a type of the battery device may be discriminated based on the simple structure, and there is no need to prepare separate battery devices for multiple types of an electronic apparatus having mounting portions with different structures and thus one battery device may be commonly used for the multiple types.

FIGS. 1 to 17 show examples of embodiments of the present invention. Specifically, FIGS. 1 to 3 show a first example of a battery device according to an embodiment of the present invention, where FIG. 1 is an oblique view, FIG. 2A is a bottom view, FIG. 2B is a left side view, FIG. 3A is a front view, FIG. 3B is a rear view, and FIG. 3C is a D-D line cross-sectional view of FIG. 2B. FIGS. 4 to 7 show an imaging device as an example of an electronic apparatus according to an embodiment of the present invention, where FIG. 4 is a front oblique view of the imaging device, FIG. 5 is a rear oblique view of the imaging device, FIG. 6 is a rear view of the imaging device, and FIG. 7 is an oblique view showing a first example of a rear panel of an exterior case. FIG. 8 is an exploded oblique view showing a mounting portion, a slide member, and a support plate member, and FIGS. 9A to 9C describe a state of mounting a battery device in a mounting portion of an imaging device, where FIG. 9A is a front view of a rear panel, FIG. 9B is a view describing an initial state during mounting the battery device, and FIG. 9C is a view describing a state after mounting the battery device. FIG. 10 is an oblique view showing a second example of a rear panel, and FIGS. 11A to 11C describe a state of mounting a battery device in a mounting portion of an imaging device, where FIG. 11A is a front view of the rear panel, FIG. 11B is a view describing an initial state during mounting the battery device, and FIG. 11C is a view describing a state after mounting the battery device.

FIGS. 12 and 13 show a second example of a battery device according to an embodiment of the present invention, where FIG. 12 is an oblique view and FIG. 13 is a front view. FIG. 14 is an oblique view showing a third example of a rear panel, and FIG. 15 is an U-U line cross-sectional view of FIG. 14 in a state where a battery device is mounted. FIG. 16 is a front oblique view of a fourth example of a mounting portion of an electronic apparatus according to an embodiment of the present invention, and FIG. 17 is a view describing a mounting portion in which a battery device is mounted, the mounting portion having a dimension in a height direction Z2 sufficiently larger than that of the battery device.

Example 1

First, a first example of a battery device according to an embodiment of the present invention will be described with reference to FIGS. 1 to 3. The battery device 1 includes: a battery enclosure 2 formed with a hollow enclosure; a battery cell and a control circuit board (not shown) provided inside the battery enclosure 2; and a battery side output terminal 3 provided in the battery enclosure 2.

As shown in FIG. 1, the battery enclosure 2 shown in this example is formed as an approximately rectangular parallelepiped block-shaped container having a dimension L in a longitudinal direction Y, a dimension W in a crosswise direction X at right angles to the longitudinal direction Y, and a dimension H in a height direction Z at right angles to the longitudinal direction Y and the crosswise direction X. In this example, the dimensions of the battery enclosure 2 (length L, width W, and height H) are set to have a relation of: length L>width W>height H. However, a shape of a battery device according to an embodiment of the present invention is not limited to a shape of the battery device of this example, and the height H (for example, width W<height H) is sufficiently be increased, to allow the width W longer than the length L (length L<width W), and to use other variations in the dimensions, for example. The battery enclosure 2 is formed with a container-shaped upper case 4 with one surface open and a cover-shaped lower case 5 mounted to close the opening of the upper case 4.

The upper case 4 has a rectangular upper surface 4 a, a front surface 4 b, a rear surface 4 c, a left side surface 4 d, and a right side surface 4 e. The front surface 4 b is continuous with the upper surface 4 a to be approximately perpendicular to one side Y of the upper surface 4 a in the longitudinal direction. The rear surface 4 c is continuous with the upper surface 4 a to be approximately perpendicular to the other side Y of the upper surface 4 a in the longitudinal direction. The left side surface 4 d is continuous with the upper surface 4 a to be approximately perpendicular to one side of the upper surface 4 a in the crosswise direction X. The right side surface 4 e is continuous with the upper surface 4 a to be approximately perpendicular to the other side of the upper surface 4 a in the crosswise direction X. Circular chamfers 4 f, 4 f each having a large radius of curvature are provided in a corner at which the upper surface 4 a intersects with the left side surface 4 d and a corner at which the upper surface 4 a intersects with the right side surface 4 e, respectively.

The lower case 5 is formed with a lower surface 5 a, a front surface 5 b, a rear surface 5 c, a left step portion 5 d, and a right step portion 5 e. The lower surface 5 a is approximately rectangular and shows a specific example of a second surface of the battery enclosure 2. The front surface 5 b forms part of a first surface continuous with the lower surface 5 a to be approximately perpendicular to one side of the lower surface 5 a in the longitudinal direction Y. The rear surface 5 c has a third step surface 6 c continuous with the lower surface 5 a with a predetermined step from the other side in the longitudinal direction Y of the lower surface 5 a. The left step portion 5 d has a first step surface 6 a continuous with the lower surface 5 a with a predetermined step from one side of the lower surface 5 a in the crosswise direction X. The right step portion 5 e has a second step surface 6 b continuous with the lower surface 5 a with a predetermined step from the other side of the lower surface 5 a in the crosswise direction X. The front surface 5 b of the lower case 5 and the front surface 4 b of the upper case 4 form a front surface that is the first surface of the battery enclosure 2.

An application portion 5 f for application of a label is formed to have an appropriate depth on the lower surface 5 a of the lower case 5. As shown in FIG. 3A, the first step surface 6 a and the second step surface 6 b are set to have an approximately equal height S (length in the height direction Z) from the lower surface 5 a. Further, the first step surface 6 a and the second step surface 6 b are also set to have an approximately equal width M (length in the crosswise direction X). The first step surface 6 a and the second step surface 6 b are formed to be approximately parallel to the lower surface 5 a, respectively.

Further, as shown in FIG. 1A, a first engaging portion 7 and a second engaging portion 8 are provided in the lower case 5, where the first engaging portion 7 is formed protruding from one side of the lower surface 5 a with predetermined width N and thickness T in the crosswise direction X that is the second surface, and the second engaging portion 8 is formed protruding with predetermined width N and thickness T from the other side of the lower surface 5 a in the crosswise direction X. The first engaging portion 7 and the second engaging portion 8 are symmetrical with each other, and the width (protrusion length) N of each of the first engaging portion 7 and the second engaging portion 8 is set to be about ½ the width M of each of the first step surface 6 a and the second step surface 6 b. The thickness T of each of the first engaging portion 7 and the second engaging portion 8 is set to be ½ or less the height S of each of the first step surface 6 a and the second step surface 6 b.

The first engaging portion 7 has a first engaging piece 7 a, a second engaging piece 7 b, and a third engaging piece 7 c provided at appropriate intervals in the longitudinal direction Y. The first engaging portion 7 a is placed on a front surface 5 b side, the third engaging portion 7 c is placed on a rear surface 5 c side, and the second engaging portion 7 b is placed in a middle between the first engaging portion 7 a and the third engaging portion 7 c. A first opening 10 a is provided between the first engaging piece 7 a and the second engaging piece 7 b, and a second opening 10 b is provided between the second engaging piece 7 b and the third engaging piece 7 c. Similarly, the second engaging portion 8 has a first engaging piece 8 a, a second engaging piece 8 b, and a third engaging piece 8 c provided at appropriate intervals in the longitudinal direction Y. The first engaging portion 8 a is placed on a front surface 5 b side, the third engaging portion 8 c is placed on a rear surface 5 c side, and the second engaging portion 8 b is placed in a middle between the first engaging portion 8 a and the third engaging portion 8 c. A third opening 10 c is provided between the first engaging piece 8 a and the second engaging piece 8 b, and a fourth opening 10 d is provided between the second engaging piece 8 b and the third engaging piece 8 c.

Further, as shown in FIGS. 2 and 2A, a first rib 11 a is provided on a rear surface 5 c side of the first engaging piece 7 a of the first engaging portion 7; a second rib 11 b is provided on a rear surface 5 c side of the second engaging piece 7 b; and a third rib 11 c is provided on a rear surface 5 c side of the third engaging piece 7 c. Similarly, a first rib 12 a is provided on a rear surface 5 c side of the first engaging piece 8 a of the second engaging portion 8; a second rib 12 b is provided on a rear surface 5 c side of the second engaging piece 8 b; and a third rib 12 c is provided on a rear surface 5 c side of the third engaging piece 8 c. A protrusion length (width) P of each of the first ribs 11 a, 12 a and the second ribs 11 b, 12 b is set to be about ½ a protrusion length (width) N of each of the first engaging pieces 7 a, 8 a and the second engaging pieces 7 b, 8 b. On the other hand, a protrusion length (width) of each of the third ribs 11 c, 12 c is set to be approximately equal to a protrusion length (width) N of each of the third engaging pieces 7 c, 8 c.

An opening 14 for the output terminal 3 to expose part of the output terminal 3 is provided on a front surface 5 b side of the lower case 5. The opening 14 is formed as a continuous notch from the front surface 5 b to the lower surface 5 a and is provided to notch a whole approximate center of the front surface 5 b in the crosswise direction X. Further, two first discrimination recesses 15 a, 15 b to discriminate a type of the battery device 1 are provided on both sides of the opening 14 of the lower case 5 in the crosswise direction X. The two first discrimination recesses 15 a, 15 b are each formed to have a specific shape according to a shape, a power capacity, or the like of the battery device 1.

As shown in FIGS. 1 and 2B, two second discrimination recesses 9 a, 9 b to discriminate a type of the battery device 1 are provided on the first step surface 6 a at a predetermined interval in the longitudinal direction Y. Similarly, two third discrimination recesses 13 a, 13 b to discriminate a type of the battery device 1 are provided on the second step surface 6 b at a predetermined interval in the longitudinal direction Y. The second discrimination recesses 9 a, 9 b are each formed to have a specific depth (height) K from the first step surface 6 a and the third discrimination recesses 13 a, 13 b are each formed to have a specific depth (height) J from the second step surface 6 b according to a shape, a power capacity, and others of the battery device 1. In this example, the second discrimination recesses 9 a, 9 b and the third discrimination recesses 13 a, 13 b are approximately symmetrically formed so that the depth K is approximately equal to the depth J. However, the depth K of the second discrimination recesses 9 a, 9 b and the depth J of the third discrimination recesses 13 a, 13 b in an embodiment of the present invention are not limited to those in this example, and the second discrimination recesses 9 a, 9 b and the third discrimination recesses 13 a, 13 b may be asymmetrically formed to make the depth K differ from the depth J.

In this example, the number of the second discrimination recesses 9 or the third discrimination recesses 13 is set to be two. However, the number of the second discrimination recesses 9 or the third discrimination recesses 13 is not limited to the number in this example, and the number of the second discrimination recesses 9 may be one and the number of the third discrimination recesses 13 may be three, for example. Further, in this example, the second discrimination recesses 9 and the third discrimination recesses 13 are formed in each of the first step surface 6 a and the second step surface 6 b; however, it is also possible to form the second discrimination recesses 9 or the third discrimination recesses 13 on either one of the first step surface 6 a and the second step surface 6 b. The second discrimination recesses 9 a, 9 b and the third discrimination recesses 13 a, 13 b show a specific example of a recess in an embodiment of the present invention.

As shown in FIGS. 1 and 3A, the output terminal 3 mounted on the opening 14 of the lower case 5 has a block-shaped terminal holder 16 having at least: a front surface 16 coplanar with the front surface 5 b of the lower case 5; and a lower surface 16 b approximately perpendicular to the front surface 16 a and coplanar with the lower surface 5 a of the lower case 5. The terminal holder 16 has: multiple (four in this example) electrode slits 17 a, 17 a in which electrodes are placed; and two positioning slits 17 b, 17 b placed on both sides of the multiple electrode slits 17 a. The electrode slits 17 a and the positioning slits 17 b are formed in a corner of the terminal holder 16 as groove-shaped notches continuous from the front surface to the bottom surface.

Positioning protrusions of a connection terminal 56 provided in a mounting portion of an electronic apparatus described later are each engaged with the two positioning slits 17 b of the terminal holder 16. Similarly, electrodes of the connection terminal 56 are each engaged with the four electrode slits 17 a. Battery side electrodes of the output terminal 3 (not shown) are each placed in the four electrode slits 17 a. The battery cell incorporated in the battery enclosure 2 is electrically connected to each of the battery side electrodes of the output terminal 3.

The lower case 5 having such a configuration is overlapped with the upper case 4 to close an opening of the upper case 5 and portions overlapped in this manner are joined together. Obviously, the portions may be joined together by use of an adhesive, by thermally welding, or by another joining method, for example. Accordingly, the battery enclosure 2 is formed having the upper case 4 and the lower case 5 integrated. A battery cell having one or more battery cells and a control circuit board having a microcomputer including a CPU, a RAM and ROM, and an interface are stored in the battery enclosure 2. The battery cell and the control circuit board are electrically connected to each other and also connected to the output terminal 3. The output terminal 3 is formed so that power of the battery cell may be output and data of information on a battery capacity, a property, and others may be communicated between the output terminal 3 and external electronic apparatus. The battery device 1 is formed in this manner.

Next, a first example of an imaging device included in suitable electronic apparatus using the battery device 1 as a portable power source will be described with reference to FIGS. 4 to 6. The device shown in FIGS. 4 to 6 is a digital video camera 20 used as a first example of an imaging device. The digital video camera 20 includes a tape cassette having a magnetic tape as an information storage medium and converts an optical image into electric signals using an imaging element (such as a CCD (charge coupled device) or a CMOS image sensor) showing a specific example of an imaging mechanism, so that the image information may be recorded in the magnetic tape and displayed in a display device 23 formed with a flat panel such as a liquid crystal display.

However, an information storage medium used in an imaging device showing a specific example of an electronic apparatus according to an embodiment of the present invention is not limited to the magnetic tape shown in this example. It is possible to use disc-shaped recording media such as recordable optical discs, magneto-optical discs, and magnetic discs including DVD-Rs, DVD-RWs, DVD-RAMS, MOs, and FDs as information storage media. An electronic apparatus using such a disc-shaped recording medium may be realized as an optical disc video camera when using an optical disc; or a magneto-optical disc still camera when using a magneto-optical disc, for example. Further, such an electronic apparatus may be realized as a magnetic disc electronic organizer when using a magnetic disc.

The digital video camera 20 has: an exterior case 21 showing a specific example of a case main body formed with an enclosure forming an appearance; a tape drive device that is stored in the exterior case 21 and drives a magnetic tape of a tape cassette detachably mounted on the tape drive device to record (write) and reproduce (read) information signals; a control circuit to control driving of the tape drive device; a lens device 22 to incorporate a subject image as light to guide the image to the imaging device; and a display device rotatably attached to the exterior case 21.

As shown in FIGS. 4 to 6, the exterior case 21 is formed with a hollow enclosure and formed in an approximately rectangular parallelepiped shape by a driving device side panel 21A and a display device side panel 21B placed opposite to each other in a transverse direction; a front panel 21C to close a front opening of an enclosure formed with combining both panels; and a rear panel 21D to close a rear opening of the enclosure. The exterior case 21 has a longitudinal direction Y set to be a back-and-forth direction and is used as raised in a crosswise direction X. A lens device 22 is provided in an upper portion of the exterior case 21 in a state where a subjective lens 24 as an imaging lens of a lens system is exposed on a front surface.

The lens device 22 is attached to the exterior case 21 in a state where an optical axis of the lens system is in a horizontal direction. An imaging element (not shown) is attached to a rear portion of the lens device 22 in the exterior case 21. A view finder device 25 is placed behind the lens device 22 to reflect a subject image input from the lens device 22. An opening is provided in the upper portion of the external case 21 to expose an accessory shoe in which accessories such as a video light and an external microphone are detachably mounted. The accessory shoe is placed immediately in front of the view finder device 25 and usually detachably covered with a shoe cap 27 to open and close the opening. Further, a light emitting portion 28 of a flash device and an incorporated stereo-type microphone 29 are placed on the front panel 21C.

As shown in FIG. 4, the display device 23 is attached to a display device side panel 21B so that an attitude of the display device 23 may be modified. The display device 23 is formed with: a flat panel (not shown) formed with a flat liquid crystal display or the like; a panel case 31 in which the flat panel is stored; and a panel support 32 to support the panel case 31 so that an attitude of the panel case may be modified with respect to the display device side panel 21B. The panel support 32 has: a horizontal rotation portion to make the panel case 31 rotatable at about 90° in a horizontal direction with a vertical axis as a rotation center; and a back-and-forth rotation portion to make the panel case 31 rotatable at about 180° in a back-and-forth direction with a horizontal axis as a rotation center.

Accordingly, the display device 23 may be freely in a state where the flat panel is stored in a side surface of the display device side panel 21B; in a state where the flat panel faces backward by rotating the panel case 31 at 90° from that state; in a state where the flat panel faces forward by rotating the panel case 31 at 180° from that state; or in a state where the flat panel is in an intermediate position among these positions. A main body operation portion 33 formed with a plurality of operation buttons is provided on a side surface of the display device side panel 21B above the display device 23.

As shown in FIG. 5, a deck cover 34 to closably cover a tape deck in which the tape cassette is detachably mounted is closably provided on the driving device side panel 21A. The tape deck is a device to transport the mounted tape cassette to a predetermined position and to draw the magnetic tape from the cassette and load the tape on a rotation drum or the like of the tape drive device, and then allow the magnetic tape to run at a predetermined speed to record (write) and/or reproduce (read) information signals. The deck cover 34 to cover the tape deck has: a power source switch 35 also used as a mode selector switch; a shutter button 36 to photograph a static image; a zoom button 37 to continuously enlarge (tele) or reduce (wide) an image within a predetermined range; an opening/closing switch 38 to lock and unlock the deck cover 34; and a video recording button 39 to photograph a moving image.

The power source switch 35 has functions to switch the power source on and off by a rotation operation and to switch a plurality of function modes to each other to repeat them by performing a rotation operation with the power source switched on. Further, a hand belt 51 is attached to the deck cover 34 and a hand pad 42 is mounted on the hand belt 51. The hand belt 51 and the hand pat 42 support a hand of a user holding the exterior case 21 to prevent dropping of the digital video camera 20, for example.

As shown in FIGS. 5 and 6, a mounting portion 44 is provided on a rear surface of the exterior case 21 as a battery housing in which the battery device 1 as a portable power source is detachably mounted. The mounting portion 44 is placed lower than an approximate center of the rear surface of the exterior case 21, and is provided to open backward in the rear panel 21D forming the rear surface of the exterior case 21. The driving device side panel 21A is provided to the right of the rear panel 21D. The video recording button 39 is placed in the driving device side panel 21A. The display device side panel 21B is provided to the left of the rear panel 21D. A light emitting button 46 of the flash device and a night shot selector switch 47 are placed in the display device side panel 21B.

As shown in FIG. 7, the rear panel 21D is formed with a panel member formed longer in a vertical direction, and the mounting portion 44 formed with a recess is formed in one surface of the rear panel D. The mounting portion 44 has a rectangular opening 45 approximately as large as the battery device 1 (precisely, the mounting portion 44 has a length in a crosswise direction X1 approximately equal to that of the opening 45, but has a length in a longitudinal direction Y1 which is a length of the battery device 1 plus a length of a clearance to allow the battery device 1 to be stored in the opening 45 by rotating the battery device 1 with one edge in the longitudinal direction of the battery device as a rotation center).

The opening 45 has a bottom surface 45 a, a lower surface 45 b, an upper surface 45 c, a left side surface 45 d, and a right side surface 45 e. The bottom surface 45 a is rectangular and shows a specific example of a second surface of the mounting portion 44. The lower surface 45 b is continuous with one side of the bottom surface 45 a in the longitudinal direction Y1 and approximately perpendicular to the bottom surface 45 a and shows a specific example of an electronic apparatus side first surface. The upper surface 45 c is continuous with the other side in the longitudinal direction Y1 of the bottom surface 45 a and approximately perpendicular to the bottom surface 45 a. The left side surface 45 d is continuous with one side in the crosswise direction X1 at right angles with the longitudinal direction Y1 of the bottom surface 45 a and approximately perpendicular to the bottom surface 45 a. The right side surface 45 d is continuous with the other side in the crosswise direction X1 of the bottom surface 45 a and approximately perpendicular to the bottom surface 45 a. The opening 45 is provided with the longitudinal direction Y1 set to be a vertical direction.

Further, an upper facing 48 protruding upward is provided on the upper surface 45 c, and an insertion hole 48 a into which an operation projection 66 is inserted is provided on the upper facing 48. A lower facing 49 is provided to be continuously projected laterally and downward in a portion ranging from a lower portion of the right side surface 45 e to the lower surface 45 b. A fitting hole 50 to which a connection terminal 56 described later is fitted is provided in an approximate center of the lower surface 45 b. The fitting hole 50 is formed as a notch continuously extending from the lower surface 45 b to a middle of the bottom surface 45 a.

There are provided, on the bottom surface 45 a of the opening 45, two first penetration holes 51 a, 51 b into which a first hook 61 described later may penetrate and two second penetration holes 52 a, 52 b into which a second hook 62 may penetrate. The two first penetration holes 51 a, 51 b are provided along the left side surface 45 d of the opening 45, where the first lower penetration hole 51 a is placed at a predetermined interval from the lower surface 45 b and the first upper penetration hole 51 b is placed at a predetermined interval from the first lower penetration hole 51 a. The two second penetration holes 52 a, 52 b are provided along the left side surface 45 d of the opening 45, where the second lower penetration hole 52 a is placed at a predetermined interval from the lower surface 45 b and the second upper penetration hole 52 b is placed at a predetermined interval from the second lower penetration hole 52 a. The first penetration holes 51 a, 51 b and the second penetration holes 52 a, 52 b are provided symmetrically with each other. The first penetration holes 51 a, 51 b and the second penetration holes 52 a, 52 b are formed as rectangular holes extending in the longitudinal direction Y1 of the opening 45 so that a first hook 61 and a second hook 62 may be moved in a vertical direction at a predetermined distance, respectively.

Further, as shown in FIGS. 9A to 9C, the first lower penetration hole 51 a is provided opposite to the first opening 10 a placed between the first engaging piece 7 a and the second engaging piece 7 b of the first engaging portion 7 of the battery device 1 mounted on the mounting portion 44. Similarly, the second lower penetration hole 52 a is provided opposite to the third opening 10 c placed between the first engaging piece 8 a and the second engaging piece 8 b of the second engaging portion 8 of the battery device 1. The first upper penetration hole 51 b is provided opposite to the second opening 10 b placed between the second engaging piece 7 b and the third engaging piece 7 c of the first engaging portion 7 of the battery device 1. Similarly, the second upper penetration hole 52 b is provided opposite to the fourth opening 10 d placed between the second engaging piece 8 b and the third engaging piece 8 c of the second engaging portion 8 of the battery device 1.

Two protrusion pieces 55 a, 55 b to position and support engagement of the battery device 1 are provided on both corners on a lower edge of the opening 45. The two protrusion pieces 55 a, 55 b are formed with a predetermined clearance from the lower surface 45 a to protrude upward from the lower surface 45 b. When the battery device 1 is mounted, the first protrusion piece 55 a is engaged with the first engaging piece 7 a of the first engaging portion 7 of the battery device 1, and the second protrusion piece 55 b is engaged with the first engaging piece 8 a of the second engaging portion 8 of the battery device 1. A connection terminal 56 is provided in an approximate center between the first protrusion piece 55 a and the second protrusion piece 55 b, where the connection terminal is detachably connected to the output terminal 3 of the battery device 1 when the battery device 1 is mounted.

The connection terminal 56 has a shape and a structure corresponding to those of an output portion of the output terminal 3 of the battery device 1. Specifically, the connection terminal 56 has: four main body side electrodes 57 that are provided corresponding to the number of electrodes of the output terminal 3 and may be inserted into the four electrode slits 17 a, respectively; and two guide pieces 58 that may be inserted into the two positioning slits 17 b, 17 b, respectively. The four main body side electrodes 57 are placed on the mounting portion 44 at equal predetermined intervals in the crosswise direction X1, and the two guide pieces 58 are provided outside the electrodes 57 at a predetermined interval.

As shown in FIG. 8, a slide member 60 is placed on a rear surface of the rear panel 21D having the mounting portion 44, and a support plate member 64 is placed on a rear surface of the slide member 60. The slide member 60 is supported with respect to the rear panel 21D slidably in a vertical direction that is the longitudinal direction Y1 in the mounting portion 44. The support plate member 64 is fixed to the rear panel 21D to prevent dropping of the slide member 60. A coil spring 65 showing a specific example of an energizing member to energize the slide member 60 away from the connection terminal 56 is present between the slide member 60 and the rear panel 21D.

The slide member 60 has: a base 60 a formed with an approximately rectangular plate smaller than the bottom surface 45 a of the opening 45; and an operation portion 60 b provided protruding upward and continuously with an upper edge of the base 60 a. The first hook 61 and the second hook 62 are provided at a predetermined interval between them on one surface of the base 60 a. The first hook 61 is placed on one side of the base 60 a in a crosswise direction X1, and the second hook 62 is placed on the other side of the base 60 a in the crosswise direction X1. The first hook 61 is formed with a first hook piece 61 a on a side remote from the operation portion 60 b and a second hook piece 61 b on a side close to the operation portion 60 b. Similarly, the second hook 62 is formed with a first hook piece 62 a on a side remote from the operation portion 60 b and a second hook piece 62 b on a side close to the operation portion 60 b.

The two hook pieces 61 a, 61 b of the first hook 61 are placed in series on the base 60 a in a longitudinal direction Y1; similarly, the two hook pieces 62 a, 62 b of the second hook 62 are placed in series on the base 60 a in the longitudinal direction Y1. The four hook pieces 61 a, 61 b, 62 a, 62 b are symmetrically placed on the base 60 a with respect to the longitudinal direction Y1. Further, nails protruding toward the operation portion 60 b are provided on tops of the four hook pieces 61 a to 62 b, respectively. Each nail having an appropriate length extends approximately parallel to the base 60 a. The four hook pieces 61 a to 62 b are slidably inserted from a rear surface side into the four penetration holes 51 a, 51 b, 52 a, 52 a of the rear panel 21D, respectively. Internal and external surfaces of a top of each nail of the four hook pieces 61 a to 62 b each preferably have an inclined plane having an appropriate size in order to facilitate engagement with and detachment from the first engaging portion 7 and the second engaging portion 8 of the battery device 1.

Further, first discrimination projections 53 a, 53 b and second discrimination projections 54 a, 54 b inserted into the second discrimination recesses 9 a, 9 b and the third discrimination recesses 13 a, 13 b of the battery device 1, respectively, are provided in the nails of the four hook pieces 61 a to 62 b, respectively. The four discrimination projections 53 a to 54 b are formed on one ends of the nails located away from the base 60 a, respectively. The four discrimination projections 53 a to 54 b have a function to discriminate the first battery device 1 mountable in the mounting portion 44 and a second battery device not mountable in the mounting portion 44, the second battery device having an external shape approximately identical to that of the first battery device 1 but not having the second discrimination recesses 9 a, 9 b and the third discrimination recesses 13 a, 13 b.

In order to obtain such a function, as shown in FIGS. 9A to 9C, the first hook piece 61 a having the first discrimination projection 53 a of the first hook 61 is provided in a position where the first hook piece 61 a may be engaged with the second engaging piece 7 b of the first engaging portion 7 of the battery device 1 mounted on the mounting portion 44 and may be inserted into the second discrimination recess 9 a. Similarly, the second hook piece 61 b having the first discrimination projection 53 b of the first hook 61 is provided in a position where the second hook piece 61 b may be engaged with the third engaging piece 7 c of the first engaging portion 7 of the battery device 1 and may be inserted into the second discrimination recess 9 b. The first hook piece 62 a having the second discrimination projection 54 a of the second hook 62 is provided in a position where the first hook piece 62 a may be engaged with the second engaging piece 8 b of the second engaging portion 8 of the battery device 1 and may be inserted into the third discrimination recess 13 a. Similarly, the second hook piece 62 b having the second discrimination projection 54 b of the second hook 62 is provided in a position where the second hook piece 62 b may be engaged with the third engaging piece 8 c of the second engaging portion 8 of the battery device 1 and may be inserted into the third discrimination recess 13 b. The first discrimination projections 53 a to 54 b show a specific example of a projection in an embodiment of the present invention.

FIG. 7 shows a state where the four hook pieces 61 a to 62 b are inserted into the four penetration holes 51 a, 51 b, 52 a, 52 b. In this insertion state, an operation projection 66 provided in the operation portion 60 b of the slide member 60 is slidably inserted into the insertion hole 48 a provided on the upper facing 48 of the rear panel 21D, and accordingly a top of the operation projection 66 protrudes toward a rear surface side. The operation projection 66 protrudes in a direction identical to those of the four hook pieces 61 a to 62 b with a height approximately equal to those of the four hook pieces 61 a to 62 b. A long hole 67 to store the coil spring 65 and an opening window 68 to avoid interference with other components are also provided in the base 60 a of the slide member 60.

A slide side spring bearing piece 69 in which one edge of the coil string 65 sits is provided on one side of the long hole 67 in the base 60 a in a longitudinal direction Y1. A rear panel 21D side spring bearing portion 71 provided opposite to the spring bearing piece 69 is inserted into the other side of the long hole 67 in the longitudinal direction Y1. The spring bearing portion 71 is provided on a rear surface of the rear panel 21D, and the coil string 65 in a compressed state is present between the spring bearing portion 71 and the spring bearing piece 69. The slide member 60 is always energized away from the connection terminal 56 by an elastic force of the coil spring 65.

The support plate member 64 slidably supports the slide member 60 between the support plate member 64 and the rear panel 21D and functions to prevent dropping of the coil spring 65. The support plate member 64 is formed smaller than the rear panel 21D but larger than the slide member 60 and is clamped and fixed to the rear panel 21D by a fixing screw. Multiple attachment brackets 64 a and fixing portions 64 b are provided in the support plate member 64.

The mounting portion 44 having such a configuration may be assembled as follows, for example. First, as shown in FIG. 8, the slide member 60 is allowed to face a rear surface of the rear panel 21D, and the support plate member 64 is placed on the rear surface of the slide member 60 to hold the slide member 60 between the rear panel 21D and the support plate member 64. Then, the four hook pieces 61 a, 61 b, 62 a, 62 b protruding on one surface of the base 60 a of the slide member 60 are inserted and allowed to penetrate into the four penetration holes 51 a, 51 b, 52 a, 52 b provided in the opening 45 of the rear panel 21D, respectively, from the rear surface of the rear panel 21D. Accordingly, tops of the four hook pieces 61 a to 62 b are each allowed to protrude into the opening 45, and a predetermined clearance is formed between an internal surface of each nail and the bottom surface 45 a of the opening 45.

At the same time, the operation projection 66 provided on a top of the operation portion 60 b of the slide member 60 is inserted and allowed to penetrate into the insertion hole 48 a provided in the upper facing 48 protruding from an upper side of the opening 45 of the rear panel 21D. Next, the coil spring 65 is allowed to be present between the spring bearing portion 71 of the rear panel 21D and the spring bearing piece 69 of the slide member 60. Thereafter, the support plate member 64 is overlapped with the slide member 60, and the support plate member 64 is clamped and fixed to the rear panel 21D by a fixing screw. Accordingly, the slide member 60 is slidably supported between the support plate member 64 and the rear panel 21D. The slide member 60 is always energized away from the connection terminal 56 by an elastic force of the coil spring 65. Assembly of the mounting portion 44 is completed in this manner, and the rear panel 21D may be assembled.

The battery device 1 may be mounted on and detached from the mounting portion 44 formed as described above in the following manner, for example. FIG. 9A is a view describing the rear panel 21D with a front view of the mounting portion 44, FIG. 9B is a view describing a state when insertion of the battery device 1 starts, and FIG. 9C is a view describing a locked state when insertion of the battery device 1 is completed. In FIGS. 9B and 9C, the three engaging pieces 8 a, 8 b, 8 c of the second engaging portion 8 are engaged with the two hook pieces 62 a, 62 b of the second hook 62 and the second protrusion piece 55 b in the same manner in which the three engaging pieces 7 a, 7 b, 7 c of the first engaging portion 7 formed symmetrically with the engaging pieces 8 a, 8 b, 8 c are engaged with the two hook pieces 61 a, 61 b of the first hook 61 and the first protrusion piece 55 a. Therefore, an operation of one set formed with the first engaging portion 7 and others is described here, and description of an operation of the other set formed with the second engaging portion 8 and others is omitted.

First, a case of mounting the battery device 1 in the mounting portion 44 will be described. In this case, as shown in FIG. 9B, a front surface on a output terminal 3 side of the battery device 1 is allowed to face a lower edge of the opening 45 of the mounting portion 44. The first engaging piece 7 a of the first engaging portion 7 and the first engaging piece 8 a of the second engaging portion 8 provided on both sides of a first surface of the battery device 1 in the crosswise direction X are each and engaged by hooking with the first protrusion piece 55 a and the second protrusion piece 55 b provided on both corners of the lower edge of the opening 45. In such an engaging state, the battery device 1 is rotated closer to the mounting portion 44 with contact areas with the two protrusion pieces 55 a, 55 b as rotation centers.

Accordingly, the second engaging piece 7 b of the battery device 1 approaches the first hook piece 61 a, the third engaging piece 7 c approaches the second hook piece 61 b, and the second engaging piece 7 b is brought into contact with the first hook piece 61 a. The battery device 1 in this state is rotated and pushed into the opening 45, so that the second engaging piece 7 b presses and moves the first hook piece 61 a toward the connection terminal 56 against an elastic force of the coil spring 65. When the second engaging piece 7 b hurdles the first hook piece 61 a, the third engaging piece 7 c is then brought into contact with the second hook piece 61 b. When the third engaging piece 7 c hurdles the second hook piece 61 b, the battery device 1 is completely inserted into the opening 45, and the lower surface 5 a as a second surface of the battery device 1 is brought into contact with the bottom surface 45 a as a second surface of the mounting portion 44.

As a result, the output terminal 3 of the battery device 1 is connected to the connection terminal 56 of the mounting portion 44. Accordingly, the battery device 1 is electrically connected to the digital video camera 20, and power of the battery device 1 is supplied to the digital video camera 20 from the output terminal 3 through the connection terminal 56. Record the subject to operate the digital video camera 20 to photograph a subject and record the subject in a recording medium and to watch photographic information recorded in the recording medium in the display device 23, for example.

In this case, the first discrimination projection 53 a provided in the first hook piece 61 a of the first hook 61 is inserted into the second discrimination recess 9 a provided on the first step surface 6 a of the battery device 1. Similarly, the second discrimination projection 54 a provided in the first hook piece 62 a of the second hook 62 is inserted into the third discrimination recess 13 a provided on the second step surface 6 b of the battery device 1. The first discrimination projection 53 b provided in the second hook piece 61 b of the first hook 61 is inserted into the second discrimination recess 9 b provided on the first step surface 6 a of the battery device 1. Similarly, the second discrimination projection 54 b provided in the second hook piece 62 b of the second hook 62 is inserted into the third discrimination recess 13 b provided on the second step surface 6 b of the battery device 1.

Since the first hook piece 61 a and the second hook piece 61 b are free in this manner, the slide member 60 slides away from the connection terminal 56 by an elastic force of the coil spring 65. As a result, as shown in FIG. 9C, the first hook piece 61 a is engaged with the second engaging piece 7 b and the second hook piece 61 b is engaged with the third engaging piece 7 c. Similarly, in the second hook 62, the first hook piece 62 a is engaged with the second engaging piece 8 b and the second hook piece 62 b is engaged with the third engaging piece 8 c. Accordingly, the battery device 1 is locked by the four hook pieces 61 a, 61 b, 62 a, 62 b engaged with the four engaging pieces 7 b, 7 c, 8 b, 8 c and fixed to the mounting portion 44.

On the other hand, it may be impossible to mount a battery device in the mounting portion 44 when the battery device does not have the second discrimination recesses 9 a, 9 b and the third discrimination recesses 13 a, 13 b corresponding to the first discrimination projections 53 a, 53 b and the second discrimination projections 54 a, 54 b on the first step surface 6 a and the second step surface 6 b, respectively.

Accordingly, the second discrimination recesses 9 a, 9 b and the third discrimination recesses 13 a, 13 b are provided in the battery device 1, and the first discrimination projections 53 a, 53 b and the second discrimination projections 54 a, 54 b corresponding to the discrimination recesses are provided in the mounting portion 44. In this manner a type of the battery device may be discriminated based on a simple structure without further complicating a shape of the first discrimination recesses 15 a, 15 b of the battery device 1, even if the number of types of the battery device is further increased.

When the battery device 1 mounted on the mounting portion 44 is removed, a user manually operates the operation projection 66 toward a disengaging side as shown in FIG. 9C. Specifically, in this example, the user presses the operation projection 66 to allow the slide member 60 to slide toward the connection terminal 56 against an elastic force of the coil spring 65. The slide member 60 is moved to a place where the four hook pieces 61 a, 61 b, 62 a, 62 b are detached from the four engaging pieces 7 b, 7 c, 8 b, 8 c, so that the battery device 1 may be removed. Consequently, the battery device 1 may be removed from the mounting portion 44 by raising an edge opposite to the output terminal 3 of the battery device 1 and rotating the battery device 1 with the two first engaging pieces 7 a, 8 a engaged with the two protrusion pieces 55 a, 55 b as centers.

FIGS. 10 and 11A show a second example of a mounting portion of an electronic apparatus according to an embodiment of the present invention. This mounting portion 74 differs from the mounting portion 44 of the first example in that a first hook 81 and a second hook 82 are securely fixed in an opening 75 of a rear panel 73 and a stopper member 77 is provided to limit movement of the battery device 1 mounted on a predetermined position of the mounting portion 74. Since the mounting portion is formed in the same manner as in the first example except for that point, the same components as in the first example are indicated by the same symbols and their repeated description is omitted, and different components are selectively described.

The opening 75 of the rear panel 73 has: a bottom surface 75 a as an approximately rectangular second surface of the mounting portion 74; a lower surface 75 b as a first surface continuous with one side of the bottom surface 75 a in a longitudinal direction Y1 and approximately perpendicular to the bottom surface 75 a; a left side surface 75 d continuous with one side of the bottom surface 75 a in a crosswise direction X1 at right angles to the longitudinal direction Y1 and approximately perpendicular to the bottom surface 75 a; and a right side surface 75 e continuous with the other side of the bottom surface 75 a in the crosswise direction X1 and approximately perpendicular to the bottom surface 75 a. The opening 75 for the mounting portion 74 is formed with the bottom surface 75 a, the lower surface 75 b, the left side surface 75 d, and the right side surface 75 e. The opening 75 is provided in the rear panel 73 with the longitudinal direction Y1 set to be a vertical direction.

The first hook 81 has: a first hook piece 81 a placed on a connection terminal 56 side; and a second hook piece 81 b placed at a predetermined interval in the longitudinal direction Y1 from the first hook piece 81 a. The first hook piece 81 a is formed protruding inward from and integrally with the left side surface 75 d of the rear panel 73. A first protrusion piece 55 a is provided on a connection terminal 56 side of the first hook piece 81 a. Similarly, the second hook 82 has: a first hook piece 82 a placed on a connection terminal 56 side; and a second hook piece 82 b placed at a predetermined interval in the longitudinal direction Y1 from the first hook piece 82 a. The first hook piece 82 a is formed protruding inward from and integrally with the right side surface 75 e of the rear panel 73. A second protrusion piece 55 b is provided on a connection terminal 56 side of the first hook piece 82 a.

The second hook piece 81 b of the first hook 81 is formed continuously and integrally with the bottom surface 75 a and the left side surface 75 d of the opening 75. The second hook piece 82 b of the first hook 82 is formed continuously and integrally with the bottom surface 75 a and the right side surface 75 e of the opening 75. Cast holes 78 for injection molding using a die are formed in the bottom surface 75 a for the four hook pieces 81 a, 81 b, 82 a, 82 b and the left and right protrusion pieces 55 a, 55 b, respectively. A second discrimination projection 79 to discriminate a type of the battery device 1 is provided between the second protrusion piece 55 b and a fitting hole 50 for a connection terminal 56.

Further, as in the first example, discrimination projections 53 a, 53 b, 54 a, 54 b inserted into the second discrimination recesses 9 a, 9 b and the third discrimination recesses 13 a, 13 b of the battery device 1, respectively, are provided in nails of the four hook pieces 81 a to 82 b, respectively. The four first discrimination projections 53 a to 54 b are formed protruding away from the bottom surface 75 a on external surfaces of the nails, respectively.

The stopper member 77 is placed to be brought into contact with the right side surface 75 e on a side opposite to the lower surface 75 b of the mounting portion 74. The stopper member 77 is formed with: a stopper 77 a protruding toward an upper portion of the battery device 1 mounted on the mounting portion 74 to regulate upward movement in the longitudinal direction Y1 of the battery device 1; and an operation portion 77 b continuous with the stopper 77 a and protruding forward from the opening 75. The stopper member 77 is energized by an elastic member (not shown) to always protrude forward. At this time, the stopper 77 a protrudes toward an upper portion of the battery device 1, so that the battery device 1 is prevented from being moved and dropped from the mounting portion 74. When the operation portion 77 b is pressed against an elastic force of the elastic member to move the stopper 77 a backward, a surface of the stopper 77 a is pressed down to a place coplanar with the bottom surface 75 a. Accordingly, the battery device 1 may be moved in the longitudinal direction Y1.

The battery device 1 of the first example of an embodiment of the present invention may be mounted on and detached from the mounting portion 74 having such a configuration as follows, for example. FIG. 11A is a view describing the rear panel 73 with a front view of the mounting portion 44, FIG. 11B is a view describing a state when insertion of the battery device 1 starts, and FIG. 11C is a view describing a locked state when insertion of the battery device 1 is completed. In FIGS. 11B and 11C, the three engaging pieces 8 a, 8 b, 8 c of the second engaging portion 8 are engaged with the two hook pieces 82 a, 82 b of the second hook 82 and the second protrusion piece 55 b in the same manner in which the three engaging pieces 7 a, 7 b, 7 c of the first engaging portion 7 formed symmetrically with the engaging pieces 8 a, 8 b, 8 c are engaged with the two hook pieces 81 a, 81 b of the first hook 81 and the first protrusion piece 55 a. Therefore, an operation of one set formed with the first engaging portion 7 and others is described here, and description of an operation of the other set formed with the second engaging portion 8 and others is omitted.

First, a case of mounting the battery device 1 in the mounting portion 74 will be described. In this case, as shown in FIG. 11B, the lower surface 5 a of the battery device 1 is allowed to face the bottom surface 75 a to make the lower surface 5 a approximately parallel to the bottom surface 75 a on an upper side (side opposite to the connection terminal 56) of the opening 75 of the mounting portion 74. The battery device 1 is pressed against an energizing force of the stopper member 77, and the first hook piece 81 a of the first hook 81 is inserted into the first opening 10 a between the first engaging piece 7 a and the second engaging piece 7 b of the first engaging portion 7. At the same time, the second hook piece 81 b of the first hook 81 is inserted into the second opening 10 b between the second engaging piece 7 b and the third engaging piece 7 c of the first engaging portion 7. Accordingly, the lower surface 5 a as a second surface of the battery device 1 is brought into contact with the bottom surface 75 a as a second surface of the mounting portion 74.

In this case, as in the aforementioned example, the first discrimination projection 53 a provided in the first hook piece 81 a of the first hook 81 is inserted into the second discrimination recess 9 a provided on the first step surface 6 a of the battery device 1. Similarly, the second discrimination projection 54 a provided in the first hook piece 82 a of the second hook 82 is inserted into the third discrimination recess 13 a provided on the second step surface 6 b of the battery device 1. The first discrimination projection 53 b provided in the second hook piece 81 b of the first hook 81 is inserted into the second discrimination recess 9 b provided on the first step surface 6 a of the battery device 1. Similarly, the second discrimination projection 54 b provided in the second hook piece 82 b of the second hook 82 is inserted into the third discrimination recess 13 b provided on the second step surface 6 b of the battery device 1.

Next, the battery device 1 is allowed to slide toward the connection terminal 56. Accordingly, as shown in FIG. 11C, in the first hook 81, the second engaging piece 7 b is engaged with the first hook piece 81 a and the third engaging piece 7 c is engaged with the second hook piece 81 b. Similarly, in the second hook 82, the second engaging piece 8 b is engaged with the first hook piece 82 a and the third engaging piece 8 c is engaged with the second hook piece 82 b. Accordingly, the battery device 1 is locked by the four hook pieces 81 a, 81 b, 82 a, 82 b engaged with the four engaging pieces 7 b, 7 c, 8 b, 8 c. At the same time, the stopper member 77 is energized to outside, so that the stopper 77 a protrudes toward an upper portion of the battery device 1 and the stopper 77 is brought into contact with the third step surface 6 c of the battery device 1. This prevents the battery device 1 from being moved in the longitudinal direction Y1 and dropped from the mounting portion 74.

At this time, the output terminal 3 of the battery device 1 is connected to the connection terminal 56 of the mounting portion 74. Accordingly, the battery device 1 is electrically connected to the digital video camera 20, and power of the battery device 1 is supplied to the digital video camera 20 from the output terminal 3 through the connection terminal 56. Accordingly, the digital video camera 20 may be operate to photograph a subject and record the subject in a recording medium and to watch photographic information recorded in the recording medium in the display device 23, for example.

Further, it may be impossible to mount a battery device in the mounting portion 74 when the battery device does not have the second discrimination recesses 9 a, 9 b and the third discrimination recesses 13 a, 13 b corresponding to the first discrimination projections 53 a, 53 b and the second discrimination projections 54 a, 54 b on the first step surface 6 a and the second step surface 6 b, respectively.

Accordingly, the mounting portion 74 of this example has the first discrimination projections 53 a, 53 b and the second discrimination projections 54 a, 54 b in addition to the discrimination projection 79 used heretofore. Accordingly, it is possible to discriminate a type of the battery device based on a simple structure without complicating a shape of the discrimination projection 79, even if the number of types of the battery device is further increased. The battery device 1 may be mounted not only in the mounting portion 44 of the first example but also the mounting portion 74 of the second example having a different mounting structure.

Next, when the battery device 1 mounted on the mounting portion 74 is removed, a user manually operates the operation portion 77 b toward a disengaging side as shown in FIG. 11C. Specifically, in this example, the user presses the operation portion 77 b to press a surface of the stopper 77 a of the stopper member 77 down to a plane coplanar with the bottom surface 75 a against an energizing force of the elastic body. The battery device 1 is allowed to slide to a place where the four engaging pieces 7 b, 7 c, 8 b, 8 c are detached from the four hook pieces 81 a, 81 b, 82 a, 82 b. Accordingly, the four engaging pieces 7 b, 7 c, 8 b, 8 c are disengaged from the four hook pieces 81 a, 81 b, 82 a, 82 b, and the battery device 1 may be removed. At this time, the output terminal 3 of the battery device 1 is pulled from the connection terminal 56, and the battery device 1 is electrically disconnected from the digital video camera 20. Consequently, the battery device 1 may be removed by pulling the battery device 1 away from the opening 75.

FIGS. 12 and 13 show a second example of a battery device according to an embodiment of the present invention. The battery device 1A of the second example differs from the battery device 1 of the first example in that a second discrimination recess 9A is provided by chamfering a corner of a first step surface 6 aA over a predetermined length R in a longitudinal direction Y from one edge on an output terminal 3 side, and similarly a third discrimination recess 13A is provided by chamfering a corner of a second step surface 6 bA over the predetermined length R in the longitudinal direction Y from one edge on an output terminal 3 side. The battery device 1A is formed in the same manner as in the battery device 1 of the first example except for that point.

In this example, the length R of each of the second discrimination recess 9A and the third discrimination recess 13A in the longitudinal direction Y is set to be approximately equal to or less than a length between one edge on the output terminal 3 side and each of the third ribs 11 c, 12 c. However, the length R of each of the second discrimination recess 9A and the third discrimination recess 13A in an embodiment of the present invention is not limited to the length in this example, and may be variously modified according to a type of the battery device. For example, the second discrimination recess 9A and the third discrimination recess 13A may be asymmetrically formed to have different lengths R in the longitudinal direction Y. It is also possible to form the second discrimination recess 9A or the third discrimination recess 13A on either one of the first step surface 6 aA and the second step surface 6 bA. Further, it is also possible to variously modify a chamfering depth of a corner of each of the first step surface 6 aA and the second step surface 6 bA.

FIGS. 14 and 15 show a third example of a mounting portion of an electronic apparatus according to an embodiment of the present invention which corresponds to the battery device 1A of the second example. The mounting portion 74A differs from the mounting portion 74 of the second example in that first discrimination projections 53 aA, 53 bA and second discrimination projections 54 aA, 54 ba provided in nails of a first hook 81A and a second hook 82A, respectively, are each formed to have a shape corresponding to a shape of each of the second discrimination recess 9A and the third discrimination recess 13A of the battery device 1A. The mounting portion 74A is formed in the same manner as in the mounting portion 74 of the second example except for that point.

In this example, as shown in FIGS. 14 and 15, inclined planes corresponding to an inclination angle of the second discrimination recess 9A of the battery device 1A are provided on side surfaces of a first hook piece 81 aA and a second hook piece 81 bA of the first hook 81A. Inclined planes formed continuously and integrally with an inclined plane on a side surface of the first hook 81A are provided on side surfaces of the first discrimination projections 53 aA, 53 bA. Similarly, inclined planes corresponding to an inclination angle of the third discrimination recess 13A of the battery device 1A are provided on side surfaces of a first hook piece 82 aA and a second hook piece 82 bA of the second hook 82A. Inclined planes formed continuously and integrally with an inclined plane on a side surface of the second hook 82A are provided on side surfaces of the second discrimination projections 54 aA, 54 bA.

FIG. 16 shows a fourth example of a mounting portion of an electronic apparatus according to an embodiment of the present invention which corresponds to the battery device 1A of the second example. The mounting portion 104 of this example is formed with a hollow battery holder 103.

The mounting portion 104 has a bottom surface 105 a, a lower surface 105 b, an opening surface 105 c, a left side surface 105 d, a right side surface 105 e, and a front surface 105 f. The bottom surface 105 a is an approximately rectangular second surface of the mounting portion 104. The lower surface 105 b has a first surface continuous with one side of the bottom surface 105 a in a longitudinal direction Y2 and approximately perpendicular to the bottom surface 105 a. The opening surface 105 c is opposite to the lower surface 105 b and opened in a shape identical to that of the lower surface 105 b. The left side surface 105 d has a left step surface 107 a continuous with the bottom surface 105 a with a predetermined step on one side of the bottom surface 105 a in a crosswise direction X2 at right angles to the longitudinal direction Y2 and is approximately perpendicular to the bottom surface 105 a. The right side surface 105 e has a right step surface 107 b continuous with the bottom surface 105 a with a predetermined step on the other side of the bottom surface 105 a in the crosswise direction X2 and is approximately perpendicular to the bottom surface 105 a. The front surface 105 f is opposite to the bottom surface 105 a and continuous with and approximately perpendicular to the lower surface 105 b. A corner at which the front surface 105 f intersects with the left side surface 105 d and a corner at which the front surface 105 f intersects with the right side surface 105 e are each formed in a circular shape having a large radius of curvature. Further, the mounting portion 104 is formed with the bottom surface 105 a, the lower surface 105 b, the opening surface 105 c, the left side surface 105 d, the right side surface 105 e, and the front surface 105 f. The mounting portion 104 is provided in the battery holder 103 with the longitudinal direction Y2 set to be a vertical direction.

The left step surface 107 a and the right step surface 107 b are each set to have a length in a height direction Z2 (height) from the bottom surface 105 a which is approximately equal to a height of each of the first step surface 6 aA and the second step surface 6 bA of the battery device 1A. Further, the left step surface 107 a and the right step surface 107 b are formed to be approximately parallel to the bottom surface 105 a, respectively. In addition, as shown in FIG. 16, the mounting portion 104 has: a left connection surface 106 a that connects one side of the bottom surface 105 a in the crosswise direction X2 to one side of the left step surface 107 a in the crosswise direction X2 and is approximately perpendicular to the bottom surface 105 a and the left step surface 107 a; and a right connection surface 106 b that connects the other side of the bottom surface 105 a in the crosswise direction X2 to one side of the right step surface 107 b in the crosswise direction X2 and is approximately perpendicular to the bottom surface 105 a and the right step surface 107 b.

The left connection surface 106 a has a first hook 111 provided continuously with the left connection surface 106 a and having a predetermined length from one edge on a lower surface 105 b side in the longitudinal direction Y2. The first hook 111 is formed integrally with the left connection surface 106 a to protrude inward from the left connection surface 106 a with predetermined width and thickness. Similarly, the right connection surface 106 b has a second hook 112 provided continuously with the right connection surface 106 b and having a predetermined length from one edge on a lower surface 105 b side in the longitudinal direction Y2. The second hook 112 is formed integrally with the right connection surface 106 b to protrude inward from the right connection surface 106 b with predetermined width and thickness.

A corner at which the left step surface 107 a intersects with the left side surface 105 d has a first discrimination projection 113 provided continuously and integrally with the corner and having a predetermined length from one edge on a lower surface 105 b side in the longitudinal direction Y2. The first discrimination projection 113 is formed to connect the left step surface 107 a to the left side surface 105 d at a predetermined inclination angle. Similarly, a corner at which the right step surface 107 b intersects with the right side surface 105 e has a second discrimination projection 114 provided continuously and integrally with the corner and having a predetermined length from one edge on a lower surface 105 b side in the longitudinal direction Y2. The second discrimination projection 114 is formed to connect the right step surface 107 b to the right side surface 105 e at a predetermined inclination angle.

The battery device 1A may be mounted on and detached from the mounting portion 104 having such a configuration as follows, for example. First, a case of mounting the battery device 1A in the mounting portion 104 will be described. In this case, the front surface 5 b as a first surface of the battery device 1A is allowed to face the opening surface of the mounting portion 104 on an upper side of the mounting portion 104. Then, the first engaging portion 7 of the battery device 1A is engaged with the first hook 111, and similarly the second engaging portion 8 of the battery device 1A is engaged with the second hook 112. Next, the battery device 1A is inserted into the mounting portion 104 along the first hook 111 and the second hook 112 until the output terminal 3 is engaged with the connection terminal 56.

Accordingly, the first hook 111 is engaged with the first engaging piece 7 a, the second engaging piece 7 b, and the third engaging piece 7 c of the first engaging portion 7 of the battery device 1A. Similarly, the second hook 112 is engaged with the first engaging piece 8 a, the second engaging piece 8 b, and the third engaging piece 8 c of the second engaging portion 8 of the battery device 1A. This may prevent movement of the battery device 1A in the height direction Z2. As shown in FIG. 17, according to this example, the battery device 1A may be stored in the mounting portion 104A having a dimension in the height direction Z2 larger than that of the battery device 1A.

A protrusion length (width) of each of the third ribs 11 c, 12 c most distant from the output terminal 3 of the battery device 1A is set to be approximately equal to a protrusion length (width) N of each of the third engaging pieces 7 c, 8 c. Accordingly, the third ribs 11 c, 12 c are brought into contact with the first hook 111 and the second hook 112 when the battery device 1A is inserted into the mounting portion 104 from the rear surface. Therefore, a user may immediately understand that the battery device 1A is inserted in a wrong direction.

Next, a user may remove the battery device 1A mounted on the mounting portion 104 by holding portion of the battery device 1A exposed from the mounting portion 104 and pulling out the battery device upward. It is also possible to remove the battery device 1A by pushing the battery device 1A out of the mounting portion 104 using a battery device removing portion (not shown).

The battery device 1A having such a configuration may also exhibit the same effect as in the battery device 1 of the first example. That is, it is possible to discriminate a type of the battery device based on a simple structure without further complicating a shape of the first discrimination recesses 15 a, 15 b of the battery device 1, even if the number of types of the battery device is further increased. Further, the battery device 1A may be mounted on mounting portions having different mounting structures and thus may be effectively used.

As described above, according to a battery device, an electronic apparatus, and a battery system according to embodiments of the present invention, it is possible to discriminate a type of the battery device even when the battery device and the electronic apparatus have different attachment structures, one battery device may be used for multiple types of an electronic apparatus, and, on the contrary, one battery device may be used as an exclusive component for one type of an electronic apparatus. Accordingly, undesired use of a battery device may be prevented, and a predetermined battery device may be used for a predetermined type of an electronic apparatus to improve safety. A type of the battery device may be discriminated in multiple stages by changing a length, width, or position of a projection.

The present invention is not limited to the embodiments described above and shown in the drawings, and various modifications may be effected without departing from the gist of the present invention. For example, in the aforementioned example, a battery device according to an embodiment of the present invention is used for a digital video camera as a specific example of an imaging device; however, the battery device may be used not only for a digital video camera, obviously, but also for various other types of an electronic apparatus such as an electronic still camera, a personal computer, an electronic dictionary, a DVD player, and a car navigation system. In the aforementioned example, an example is described where six engaging pieces are provided in a battery device and four hook pieces or two hooks are provided in a mounting portion; however, it is obvious that the number of the engaging pieces is not limited to six, the number of the hook pieces is not limited to four, and the number of the hooks is not limited to two.

It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and alterations may occur depending on design requirements and other factors insofar as they are within the scope of the appended claims or the equivalents thereof. 

1-8. (canceled)
 9. A battery case to incorporate a battery cell and an output terminal to output power from the battery cell, the battery case comprising: a first surface; a second surface approximately perpendicular to the first surface; a first step surface provided with and approximately parallel to the second surface with a predetermined step on one side of the second surface in a crosswise direction; a second step surface provided with and approximately parallel to the second surface with a predetermined step on an other side of the second surface in the crosswise direction; a first engaging portion protruding from the one side of the second surface with predetermined width and thickness in the crosswise direction; a second engaging portion protruding from the other side of the second surface with predetermined width and thickness in the crosswise direction; and a recess provided in at least one of the first and second step surfaces, wherein the first step surface extends between opposing first and second ends of the first step surface in a lengthwise direction, the second step surface extends between opposing first and second ends of the second step surface in the lengthwise direction, and the first ends of the first and second step surfaces are at respective corners between the first and second step surfaces and the first surface.
 10. The battery case according to claim 9, wherein the second ends of the first and second step surfaces extend beyond an end of the second surface in the lengthwise direction.
 11. The battery case according to claim 10, further comprising: a third surface approximately perpendicular to the second surface and provided at an opposing end of the battery case with respect to the first surface; and a third step surface provided with and approximately parallel to the second surface with a predetermined step that separates the second surface from the third surface.
 12. The battery case according to claim 11, wherein third step surface connects the first step surface to the second step surface.
 13. The battery case according to claim 9, wherein the first or second engaging portion hangs over the recess in the lengthwise direction.
 14. The battery case according to claim 9, further comprising the battery cell and the output terminal, wherein the output terminal is provided at a corner between the first and second surfaces.
 15. The battery case according to claim 9, wherein the at least one of the first and second step surfaces is uneven due to the recess.
 16. The battery case according to claim 9, wherein at least one of the first step surface and the second step surface includes one or more bevels, and the at least one of the first step surface and the second step surface is uneven due to the recess and the one or more bevels.
 17. The battery case according to claim 9, further comprising: a third engaging portion protruding from the one side of the second surface with predetermined width and thickness in the crosswise direction; and a fourth engaging portion protruding from the other side of the second surface with predetermined width and thickness in the crosswise direction, wherein the third and fourth engaging portions are provided proximate to a corner between the first surface and the second surface, and the third and fourth engaging portions and the first ends of the first and second step surfaces form respective grooves between the third and fourth engaging portions and respective ones of the first ends of the first and second step surfaces, and the grooves are open to the first surface in the lengthwise direction and are respectively open to one of opposing directions of the crosswise direction.
 18. A battery case to incorporate a battery cell and an output terminal to output power from the battery cell, the battery case comprising: a first surface; a second surface approximately perpendicular to the first surface; a first step surface provided with and approximately parallel to the second surface with a predetermined step on one side of the second surface in a crosswise direction; a second step surface provided with and approximately parallel to the second surface with a predetermined step on an other side of the second surface in the crosswise direction; a first engaging portion protruding from the one side of the second surface with predetermined width and thickness in the crosswise direction; a second engaging portion protruding from the other side of the second surface with predetermined width and thickness in the crosswise direction; and recesses or steps provided in at least one of the first and second step surfaces, wherein the first step surface extends between opposing first and second ends of the first step surface in a lengthwise direction, the second step surface extends between opposing first and second ends of the second step surface in the lengthwise direction, and the first ends of the first and second step surfaces are at respective corners between the first and second step surfaces and the first surface.
 19. The battery case according to claim 18, wherein the second ends of the first and second step surfaces extend beyond an end of the second surface in the lengthwise direction.
 20. The battery case according to claim 19, further comprising: a third surface approximately perpendicular to the second surface and provided at an opposing end of the battery case with respect to the first surface; and a third step surface provided with and approximately parallel to the second surface with a predetermined step that separates the second surface from the third surface.
 21. The battery case according to claim 20, wherein third step surface connects the first step surface to the second step surface.
 22. The battery case according to claim 18, wherein the recesses or steps include a pair of first recesses or steps provided in the first step surface that are separated by a first non-recessed or non-stepped portion of the first step surface.
 23. The battery case according to claim 22, wherein the first recesses or steps form first recessed or stepped portions of the first step surface that are further apart from the second surface than the first non-recessed or non-stepped portion of the first step surface.
 24. The battery case according to claim 23, wherein the first step surface is a contiguous uneven surface that is separated from the second surface.
 25. The battery case according to claim 24, wherein: the recesses or steps include a pair of second recesses or steps provided in the second step surface that are separated by a second non-recessed or non-stepped portion of the second step surface; the second recesses or steps form second recessed or stepped portions of the second step surface that are further apart from the second surface than the second non-recessed or non-stepped portion of the second step surface; and the second step surface is a contiguous uneven surface that is separated from the second surface.
 26. The battery case according to claim 18, wherein: the first or second engaging portion hangs over one of the recesses or steps in the lengthwise direction, and the at least one of the first and second step surfaces is uneven due to the recesses or steps.
 27. The battery case according to claim 18, further comprising: a third engaging portion protruding from the one side of the second surface with predetermined width and thickness in the crosswise direction; and a fourth engaging portion protruding from the other side of the second surface with predetermined width and thickness in the crosswise direction, wherein the third and fourth engaging portions are provided proximate to a corner between the first surface and the second surface, and the third and fourth engaging portions and the first ends of the first and second step surfaces form respective grooves between the third and fourth engaging portions and respective ones of the first ends of the first and second step surfaces, and the grooves are open to the first surface in the lengthwise direction and are respectively open to one of opposing directions of the crosswise direction.
 28. A battery case to incorporate a battery cell and an output terminal to output power from the battery cell, the battery case comprising: a first surface; a second surface approximately perpendicular to the first surface; a first step surface provided with and approximately parallel to the second surface with a predetermined step on one side of the second surface in a crosswise direction; a second step surface provided with and approximately parallel to the second surface with a predetermined step on an other side of the second surface in the crosswise direction; a first engaging portion protruding from the one side of the second surface with predetermined width and thickness in the crosswise direction; a second engaging portion protruding from the other side of the second surface with predetermined width and thickness in the crosswise direction; and depressions provided in at least one of the first and second step surfaces, wherein the first step surface extends between opposing first and second ends of the first step surface in a lengthwise direction, the second step surface extends between opposing first and second ends of the second step surface in the lengthwise direction, and the first ends of the first and second step surfaces are at respective corners between the first and second step surfaces and the first surface. 